Ionocaloric Cooling: A New, Low‑Emission Way to Make Things Cold

In a development that could reshape how the world cools itself, scientists have unveiled a brand‑new refrigeration approach called ionocaloric cooling that promises high efficiency with far lower climate impact than today’s gas‑based systems. Conventional refrigerators and air conditioners work by evaporating and condensing gases—many of which, like hydrofluorocarbons (HFCs), are potent greenhouse gases. That is why nations signed the Kigali Amendment, committing to steep cuts in HFCs over the coming decades. The ionocaloric concept sidesteps those gases entirely. Instead of moving heat with a vapor, the ionocaloric cycle uses ions. Applying an electric current pushes charged particles into or out of a solvent or solid, shifting its phase boundary and forcing a material to melt or crystallize. Because melting or freezing absorbs or releases large amounts of heat, that controlled phase change becomes the cooling (or heating) engine. The approach was first modeled and demonstrated in 2023 by researchers at Lawrence Berkeley National Laboratory and UC Berkeley. In bench experiments they used a salt made from sodium and iodine to induce melting in ethylene carbonate, a solvent widely used in lithium‑ion batteries. Remarkably, the team measured a temperature swing of about 25 °C (45 °F) using less than one volt of applied potential—performance that outstrips many other caloric cooling ideas so far. Beyond raw performance, the chemistry also offers climate advantages. Ethylene carbonate can be manufactured from carbon dioxide feedstocks, meaning an ionocaloric system might have net zero—or even net negative—global warming potential depending on the materials chosen and how they’re produced. "The landscape of refrigerants is an unsolved problem," said mechanical engineer Drew Lilley of Lawrence Berkeley National Laboratory. "No one has successfully developed an alternative solution that makes stuff cold, works efficiently, is safe, and doesn't hurt the environment. We think the ionocaloric cycle has the potential to meet all those goals if realized appropriately." Co‑author Ravi Prasher, another mechanical engineer at the lab, emphasized the practical balancing act ahead: "There are three things we're trying to balance: the GWP of the refrigerant, energy efficiency, and the cost of the equipment itself. From the first try, our data looks very promising on all three of these aspects." International follow‑up work in 2025 further refined the idea, demonstrating highly efficient cycles using nitrate‑based salts that could be recycled with electric fields and membrane systems—an early hint at ways to design closed, low‑waste machines. Still, major hurdles remain before ionocaloric cooling leaves the lab. The research team notes several engineering challenges: finding robust, non‑corrosive salts and solvents that cycle many thousands of times; designing membranes and electrodes that can reliably shuttle ions without degradation; ensuring systems are safe, affordable, and manufacturable at scale; and integrating the cycle into compact, marketable units for appliances, transport refrigeration, and air conditioning. If those problems can be solved, ionocaloric devices could do more than cool. The same physics works in reverse, offering a path to efficient electric heating with a single technology platform. The ionocaloric work was published in Science and framed as a new thermodynamic cycle that draws on insights from electrochemistry, materials science, and thermal engineering. Researchers are now experimenting with a wide palette of salts and solvents to tune efficiency, operating temperatures, and durability. Policy makers watching alternatives to HFCs will be interested. Replacing vapor‑compression systems globally would cut a major source of climate risk, and a low‑GWP, electrically driven refrigeration technology meshes well with decarbonization plans that pair cleaner electricity with end‑use electrification. For consumers, the timeline is still unclear. Lab results are promising but commercial products will require years of materials testing, prototype design, and industrial investment. For now, ionocaloric cooling sits among a handful of emerging refrigeration concepts that could, collectively, shrink the climate footprint of how we keep things cold. If the technology scales, the hum of a new kind of fridge may one day be quieter on the planet as well as on your kitchen counter.